Device for a Fuel Filter System

ABSTRACT

The invention relates to a device ( 8 ) for a fuel filter system ( 10, 14 ) separating water from the fuel, characterized in that the water takes on a property enhancing the separation by means of the device ( 8 ) by the action of the medium ( 42 ).

The invention relates to a device for a fuel filter system that separates water from the fuel.

Fuel filter systems for supplying drives of a variety of kinds are configured, according to the prior art, in such a way that not only the contaminants, like suspended particles, dust, and the like, are removed, but that water is also removed. Such filter systems are used especially in diesel engines for the purpose of protecting the injection system. EP 1 669 590 A1 discloses, for example, a filter system that provides a water separation in the course of supplying fuel to motor vehicles.

High efficiency of the water separation is important for the safe and reliable operation of the systems to be supplied by a respective fuel system. Working on this basis, the object of the invention is to provide a device for a fuel filter system that guarantees an especially effective separation of the water contained in fuels, in particular, diesel fuels.

The invention achieves this object with a device having the features specified in claim 1 in its entirety.

Accordingly, the invention provides that the device causes the properties of the water to change through the use of a medium to the effect that the associated filter system improves the separation of water. This strategy offers the possibility of achieving maximum separation of the water from the so-called “pre-treated” fuel with the conventional designs of filter systems that are arranged downstream of the device according to the invention.

To this end, it is especially advantageous to proceed in such a way that the volume of water droplets increases subject to the action of the medium.

In principle, the water separation can be enhanced in that the medium to be used influences, as the precursor to the separation process taking place in the downstream filter system, the coalescing properties in a suitable way.

In order to enhance the coalescence, the water can undergo a polarization and/or ionization subject to the action of the medium.

The coalescence enhancing medium can be synthesized on the basis of salt in an especially advantageous way. The resulting effects produced in the fuel cause the water to collect so as to form larger conglomerates. The use of sodium chloride (NaCl) has proven to be especially advantageous.

It can be advantageous to configure the arrangement in such a way that the device has at least one housing for accommodating a fill amount of the salt, with which the fuel flowing into the filter system can make contact in the housing.

In this case, the housing can be inserted in an especially advantageous way into the fuel line running to the filter system and can have a fuel inlet and a fuel outlet as well as an insert comprising the salt filling. This insert, through which the fuel can flow, is located between said fuel inlet and said fuel outlet.

For this purpose, especially preferred embodiments provide that the insert containing the salt filling has the form of a cartridge that is disposed in a replaceable manner in the housing and is configured in such a way that it fills in a substantially fitting manner the housing between the inlet and the outlet. As a result, all of the fuel flow passing through the fuel line, flows through the salt filling.

In especially preferred embodiments, the cartridge forms a partial casing of the salt filling.

Such a design of the cartridge is especially advantageous when it contains salt in the loose state.

As an alternative, the cartridge can be formed by a stick containing salt in the solid state.

Preferably, the arrangement is configured so as to provide a screen, which prevents the uncontrolled leakage of salt, at least at the outlet of the housing.

It can be especially advantageous to construct this screen at one end of the casing of the cartridge so that when the cartridge is replaced, the respective screen can also be replaced at the same time.

The invention is explained in detail below by means of one exemplary embodiment that is depicted in the drawings.

FIG. 1 is a simplified function diagram of a fuel filter system that is intended for supplying fuel to a diesel engine and that is provided with an exemplary embodiment of the device according to the invention;

FIG. 2 is a perspective oblique view of the exemplary embodiment of the device that is drawn approximately to the natural size of a practical embodiment;

FIG. 3 is a longitudinal view of the exemplary embodiment;

FIG. 4 is a sectional view similar to the one in FIG. 3, but shown in a perspective oblique view; and

FIG. 5 is a simplified schematic drawing of a longitudinal view of a fuel filter system, to which the device according to the invention is assigned.

FIG. 1 is an overview of a fuel filter system for supplying a diesel engine 2 with diesel fuel from a fuel tank 4 by way of a fuel line 6, which runs to an inventive device, which is designated as a whole as 8 and of which the exemplary embodiment, to be described herein, is depicted in greater detail in FIGS. 2 to 4. The fuel line runs from the device 8 to a first water separating filter system 10 and from there by way of a fuel pump 12 to a second water separating filter system 14, from which the cleaned, water-free fuel is delivered to the motor 2 by an injection pump 16. The filter systems 10 and 14, of which the filter system 10 serves as the prefilter and the filter system 14 serves as the main filter, are shown in greater detail in FIG. 5. Instead of two water separating filter systems 10 and 14, it is also possible for just the prefilter 10 or just the main filter 14 to be water separating. The device 8 could also be disposed at any point inside the fuel line or the return line.

According to FIGS. 2 to 4, the device 8 has a housing 1 in the shape of a circularly cylindrical sleeve, which is closed at one end 18 with the exception of a centrally located fuel outlet 20. At the opposite end, the main part of the housing is closed by a screwed on closing cap 22, where a seal is provided with an O-ring 24. The cap 22 has a centrally located fuel inlet 26.

When the cap 22 is unscrewed, the interior space of the main part of the housing is accessible in order to put in an insert in the form of a salt cartridge 28, which in the housing 1 forms a salt filling 42, in the example, sodium chloride. Especially when the salt filling 42 consists of loose salt, the cartridge 28 has preferably a casing 30. The shape of the cartridge 28 is adapted to the circularly cylindrical interior space of the housing 1 in such a way that the result is a substantially abutting fit with the inner walls, so that the entire stream of fuel makes contact with or flows through the salt filling 42. In order to prevent the salt from escaping when the fuel flows through, a screen 32 is arranged upstream of the fuel outlet 20. This screen may be a part of the casing 30 or may be mounted on the end cap 22. When the screen 32 is located on the casing 30, this screen is replaced at the same time that the salt cartridge 28 is replaced. A suitable fineness of the screen 32 lies in a range of aperture diameters of 25 μm.

Instead of using loose salt inside a casing 30, the cartridge 28 can be formed by a solid block of salt or a partially plasticized stick. It has been demonstrated that after the fuel has made contact with the salt filling 42, the fuel is conditioned by the effect of the coalescing property in such a way that a significantly improved water separation is guaranteed in the respective fuel filter system 10, 14, arranged downstream of the device 8.

A suitable design of the filter system, arranged downstream of the device 8, is shown in detail in FIG. 5, where, according to the drawing in FIG. 1, a first filter system 10 is provided as the prefilter and a second filter system 14 is provided as the main filter.

FIG. 5 shows an exemplary embodiment with a filter housing, designated as a whole as 40, the upper side of which is closed tightly with a removable closing cover 3. The housing 40 has, with the exception of a bottom part 5, an essentially circularly cylindrical shape with a central vertical axis 7. A coaxial inner body 9 is inserted into the housing 1, starting from the upper side of the housing 1, which is open when the cover 3 is removed. Said coaxial inner body is sealed off from the housing walls by means of sealing arrangements 11, 13, 15, and 17. The inner body 9 forms with its coaxial inner tube 19 an evaporator housing, the details of which will be discussed below.

The outside of the inner tube 19 is adjacent to the clean side 21 of a concentric fuel filter device 23, which is mounted on the inner body 9. As shown simply by the flow arrow 27, the diesel oil is fed through a fuel inlet (not shown) to the dirt side 25 of the fuel filter system. After flowing through the filter device 23 from the outside to the inside, the diesel oil passes out of the clean side 21 to a bottom side fuel outlet 29.

The filter device 23 is constructed conventionally such that the water is separated in the separating zone 31. As indicated by the arrow 33, the separated water passes together with the diesel oil into a collection chamber 35, which is formed by the bottom housing section adjacent to the bottom part 5. Due to the specific weight of the water being higher than that of the diesel oil, in operation a bottom side sump 37 consisting of the separated water is formed in the collection chamber 35, the upper separating line between said separated water and the lighter diesel oil lying thereon being designated as reference numeral 39. The level height of the separating line 39 between the sump 37 consisting of the separated water and the diesel oil lying thereon is detected by a water level sensor 41.

As indicated with the flow arrow 43, a dispensing device 45 is attached to the bottom of the sump 37. The operation of the dispensing device can be controlled as a function of the signals of the water level sensor 41. In the present embodiment, wherein the fuel pump is disposed downstream of the fuel outlet 29 and, therefore, in operation a negative pressure prevails in the filter housing 40, the dispensing device 45 has a pump 47. The operation of said pump is controlled by means of the water level sensor 41 in such a way that in operation so much water of the sump 23 is drained from the collection chamber 35 that the separating line 39 does not fall to the connecting point on the dispensing device 45, so that the pump 47 conveys the separated water into a water receiving and evaporator device, which is designated as a whole as 49.

The inner tube 19 of the inner body 9 forms, as part of the water receiving and evaporator device 49, an evaporator housing, which extends upstream of the dispensing device 45 coaxially upward to an evaporating water outlet 51, to which is attached an evaporating water outlet 53 in the cover element 3.

In order to control the evaporation of the water 55, conveyed through the pump 47 into the evaporator housing 19, the base of the evaporator housing has an element 57 for controlled heat dissipation. In this case, it may be a separate heating device or a heat exchanger for the supply of engine heat, exhaust gas heat, or coolant heat.

Here it can be especially advantageous to use a PTC element, that is, a resistance element with a positive curve of the temperature coefficient, which in turn makes it possible to dispense with the regulating and control devices or a thermal cutoff fuse.

The water 55, delivered by the pump 47 and pre-cleaned by a gravity induced layer separation process in the collection chamber 35, evaporates to form water vapor or fog, which rises, as indicated in FIG. 5, in the inner tube 19 and passes to the outside through the evaporating water outlet 51 of the inner tube 19 and the evaporating water outlet 53 in the cover element 3.

As stated above, the water receiving and evaporator device 49 includes a safety device in the form of a valve arrangement that closes as a function of an inadmissible quantity of non-evaporated, collected water 55. For this purpose, the present embodiment provides a float valve, which has, as the closing body, a float ball 49, which interacts with a valve seat area 61 on the evaporating water outlet 51 and which closes said outlet by floating upward and resting against the valve seat area 61. In the instance that the amount of fluid controlled by the operation of the pump 47 is normal in the evaporator housing, the float ball 59 is located, as shown in FIG. 5, at a distance from the valve seat surface 61, where the ball 59 rests on holding ribs 63. 

1. A device (8) for a fuel filter system (10, 14) that separates water from the fuel, characterized in that the device (8) causes the water to assume a separation enhancing property subject to the action of a medium (42).
 2. The device (8) according to claim 1, characterized in that the volume of water droplets increases subject to the action of the medium (42).
 3. The device (8) according to claim 2, characterized in that the water undergoes a polarization subject to the action of the medium (42).
 4. The device (8) according to claim 1, characterized in that the water undergoes an ionization subject to the action of the medium (42).
 5. The device according to claim 1, characterized in that the medium (42) is synthesized on the basis of salt.
 6. The device according to claim 5, characterized in that the medium (42) contains NaCl.
 7. The device according to claim 1, characterized in that the device has at least one housing (1) for accommodating a fill amount (42) of the salt, with which the fuel flowing into the filter system (10, 14) can make contact in the housing (1).
 8. The device according to claim 7, characterized in that the housing (1) is inserted into the fuel line (6, 29) running to the filter system (10, 14) and has a fuel inlet (26) and a fuel outlet (20) as well as an insert (30) containing the salt filling (42), said insert, through which the fuel can flow or with which the fuel can make contact being located between the fuel inlet and the fuel outlet.
 9. The device according to claim 8, characterized in that the insert (30) containing the salt filling (42) has the form of a cartridge (28) that is disposed in a replaceable manner in the housing (1) and is configured in such a way that it fills in a substantially fitting manner the housing (1) between the inlet (26) and the outlet (20).
 10. The device according to claim 9, characterized in that the cartridge (28) forms a partial casing of the salt filling (42).
 11. The device according to claim 9, characterized in that the cartridge (28) contains salt in the loose state.
 12. The device according to claim 9, characterized in that the cartridge (28) is formed by a stick containing salt in the solid state.
 13. The device according to claim 7, characterized by a screen (32), which prevents the uncontrolled leakage of salt, at least at the outlet (20) of the housing (1).
 14. The device according to claim 13, characterized in that the screen (32) is formed at one end of the casing (30) of the cartridge (28). 